JP4454679B2 - Cooler equipment - Google Patents

Description

  The invention relates to a cooler device according to the front part of claim 1.

  The amount of air that can be supplied to a supercharged combustion engine depends on the pressure of the air, but also depends on the temperature of the air. Thus, supplying the maximum possible amount of air to the combustion engine requires that the compressed air be cooled in the charge air cooler before it is directed to the combustion engine. Compressed air is typically cooled by ambient air flowing through the charge air cooler. Therefore, the compressed air can be cooled to a temperature that substantially corresponds to the temperature of the surrounding environment.

A technique known as EGR (Exhaust Gas Recirculation) is a known technique that returns a portion of the exhaust gas from a combustion process in a combustion engine through a return line to an inlet line for the supply of air to the combustion engine. Is the method. Therefore, a mixture of air and exhaust gas is supplied to the engine cylinder through the inlet line and combustion occurs in the cylinder. The addition of exhaust gas to the air results in a lower combustion temperature, in particular a reduction in the content of nitric oxide NO _x in the exhaust gas. This technique is used for both Otto and diesel engines. A known implementation is to cool the exhaust gas returned by the coolant of the vehicle cooling system in the first EGR cooler and by ambient air in the second EGR cooler. Therefore, the exhaust gas can likewise be cooled to a temperature substantially corresponding to the temperature of the environment. A further known implementation is to place the charge air cooler and the second EGR cooler in close proximity to each other at the front of the vehicle, in front of the vehicle's normal radiator. Therefore, the cooled exhaust gas and the cooled compressed gas can be mixed with each other substantially immediately after cooling.

  In operating situations where the combustion engine has a low load and at the same time a low ambient temperature exists, during cooling in the EGR cooler, the exhaust gas is cooled to such a low temperature that the corrosive substances in the exhaust gas can condense. There is a risk. EGR coolers are usually formed from a corrosion resistant material such as stainless steel, so that at least for a short period of time no problems arise due to the formation of such condensate in the EGR cooler. However, the charge air cooler is usually formed from a material such as aluminum, which has good heat transfer properties, but does not have very good corrosion resistance properties. In this case, since the charge air cooler and the EGR cooler are located close to each other, the charge air cooling in which the exhaust gas or the condensate from the exhaust gas is not formed from a material having sufficient corrosion resistance. There is a risk of entering the chamber and accumulating in the charge air cooler.

  An object of the present invention is a cooler device having an EGR cooler for cooling the exhaust gas returned and a charge air cooler for cooling the compressed air, mounted close to each other, By providing a cooler device that effectively prevents cooled exhaust gas from the cooler or condensate from the exhaust gas from entering the charge cooler and accumulating in the charge cooler. is there.

  This object is achieved by a cooler device of the type mentioned in the introduction, which is characterized by the arrangement indicated in the characterizing part of claim 1. With such a tubular element, the cooled exhaust gas can be led into the tank of the charge air cooler at a location downstream of the point where the cooled air is led into the tank. Therefore, the air flow present in the tank is effective for the exhaust gas to travel in the reverse direction and enter the supply air cooler pipeline or accumulate in the upstream part of the supply air cooler tank. To prevent. The exhaust gas is therefore prevented from accumulating in the charge air cooler, and it is therefore possible to form the charge air cooler from a material that is less corrosion resistant than the EGR cooler. The returned exhaust gas and compressed air are therefore premixed in the downstream part of the tank of the charge air cooler. Thus, the inlet line to the combustion engine can be somewhat shortened.

  According to a preferred embodiment of the invention, the tubular element has a portion extending inside the tank of the charge air cooler. Therefore, no external lines are required to direct the cooled exhaust gas from the EGR cooler tank to the charge air cooler tank. Alternatively, the tubular element may have a portion that extends at least partially outside the tank of the charge air cooler. Advantageously, the tubular element has a substantially linearly extending portion inside the first tank. Therefore, the length of the tubular element can be minimized. The tubular element is preferably formed from a substantially rigid material. This facilitates mounting the tubular element in the correct position inside the tank of the charge air cooler. The tubular element may have a portion extending substantially centrally within the first tank. The result is a substantially uniform air flow around the tubular element and its exit aperture. Therefore, there is no possibility that exhaust gas from the exit aperture is guided in the opposite direction even a little. The central positioning of the outlet aperture of the tubular element within the tank of the charge air cooler provides effective mixing of exhaust gas and compressed air.

  According to a preferred embodiment of the invention, the tank of the charge air cooler has at least one curved part, and the outlet aperture of the tubular element is arranged in said curved part. There is usually a larger vortex in the curved part than in the straight part. As a result, when the exhaust gas exits the tubular element, the exhaust gas effectively mixes with the surrounding compressed air, starting in the curved portion. The outlet aperture of the tubular element may be defined by an end face that is angled such that the radially outermost end face within the curved portion is located downstream of the radially innermost end face. The tubular element is therefore provided with an outlet aperture that is oriented to facilitate the flow of exhaust gas through the curved portion. The end surface may extend along an inclined plane.

  According to a preferred embodiment of the present invention, the charge air cooler tank is mounted on top of the EGR cooler tank. This constitutes a tubular element having a portion extending from the upper part of the tank of the EGR cooler through the aperture in the lower part of the tank of the charge air cooler substantially directly into the tank of the charge air cooler. enable. In such cases, the tubular element will be a substantially vertically extending portion. Therefore, any condensate from the cooled exhaust gas that settles on the inner wall surface of the tubular element travels down and accumulates in the tank of the EGR cooler.

  According to a preferred embodiment of the invention, the tubular element is formed from stainless steel. The tubular element needs to be formed from a corrosion resistant material, since condensate from the cooled exhaust gas can settle inside the tubular element. Stainless steel is a very corrosion-resistant material and at the same time has relatively good heat transfer properties. The EGR cooler is also preferably formed primarily from stainless steel. With an EGR cooler, there is always a risk that condensate from the cooled exhaust gas will settle, for example when the ambient air is at a low temperature and the engine is at a low load. Since stainless steel has the properties indicated above, it is advantageous that the EGR cooler be formed from this material. Advantageously, the charge air cooler is mainly formed from aluminum. Compressed air does not contain the same corrosive substances as exhaust gases. Thus, the first cooler element can advantageously be formed from aluminum. Aluminum is a material that has very high heat transfer properties and is less expensive than stainless steel.

  Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 schematically shows an apparatus configuration for recirculation of exhaust gas of a supercharged combustion engine. The combustion engine 1 may be an Otto engine or a diesel engine. Such recirculation of exhaust gas is called EGR (exhaust gas recirculation). Adding exhaust gas to the compressed air that is directed to the engine's cylinders lowers the combustion temperature and therefore the content of nitric oxide (NO _x ) produced during the combustion process. The combustion engine 1 may be intended to power a large vehicle, for example. Exhaust gas from the cylinder of the combustion engine 1 is led to the exhaust line 3 through the exhaust manifold 2. Exhaust gas in the exhaust line 3 at a pressure higher than atmospheric pressure is guided to the turbine 4. Therefore, the turbine 4 is supplied with driving force, and this driving force is transmitted to the compressor 5 via the connection. The compressor 5 compresses air, which is led to the combustion engine 1 through the inlet line 6. A charge air cooler 7 is arranged in the inlet line 6 to cool the compressed air before it is directed to the combustion engine 1. The compressed air is cooled in the charge air cooler 7 by an air flow at ambient temperature.

  The return line 8 is intended to recirculate part of the exhaust gas from the exhaust line 3. The return line 8 includes an EGR valve 9, and the EGR valve 9 can block the exhaust gas flow in the return line 8 as necessary. The EGR valve 9 may be used to control the amount of exhaust gas that is directed to the inlet line 6 through the return line 8. The control unit 10 is intended to control the EGR valve 9 based on information regarding the current operating state of the combustion engine 1. The control unit 10 may be a computer unit provided with appropriate software. The return line 8 has a first EGR cooler 11, and in the EGR cooler 11, as a first step, the exhaust gas is cooled by the coolant of the cooling system of the combustion engine. The return line 8 also has a second EGR cooler 12 for cooling the exhaust gas as a second step. The exhaust gas is cooled by ambient air in the second EGR cooler 12. Therefore, the exhaust gas can be cooled to a temperature that is only a few degrees higher than the ambient temperature.

  The supply air cooler 7 and the second EGR cooler 12 are attached close to each other. They are advantageously mounted at the front of the vehicle, in front of a conventional radiator (not shown) for cooling the combustion engine 1 of the vehicle. The cooled compressed air from the supply air cooler 7 and the cooled exhaust gas from the second EGR cooler 12 are mixed and guided into the inlet aperture 6. The mixture of exhaust gas and air is led to the respective cylinders of the combustion engine 1 through the manifold 13.

  During operation of the combustion engine 1, exhaust gas in the exhaust line 3 drives the turbine 4. Therefore, the turbine 4 is provided with a driving force, which drives the compressor 5. Therefore, the compressor 5 draws air into the inlet line 6 and compresses the air. In most operating states of the combustion engine 1, the control unit 10 keeps the EGR valve 9 open so that part of the exhaust gas in the exhaust line 3 is directed into the return line 8. At this stage, the exhaust gas is at a temperature of about 600-700 ° C. When the exhaust gas in the return line 8 reaches the EGR cooler 11, the exhaust gas is cooled by the coolant of the cooling system that cools the combustion engine 1 as a first step. The exhaust gases are now subject to their main temperature drop. However, the EGR cooler 11 is limited to the maximum that the exhaust gas can be cooled only to a temperature substantially corresponding to the temperature of the coolant. The temperature of the coolant in the cooling system may vary, but is usually in the range of 80-100 ° C. during normal operation. The amount of compressed air and exhaust gas that can be supplied to the diesel engine 1 depends on the pressure of the air and exhaust gas, but also on their temperature. It is therefore important to provide substantially optimal cooling of the recirculated exhaust gas. Accordingly, the exhaust gas is guided into the second EGR cooler 12 and is cooled by the ambient air in the EGR cooler 12. Using ambient air as a cooling medium allows the exhaust gas to be cooled to a temperature close to that of the ambient air. Therefore, the exhaust gas can be cooled in the second EGR cooler 12 to substantially the same temperature as the compressed air in the charge air cooler 7.

  FIG. 2 shows a partial cross section of the charge air cooler 7 and the second EGR cooler 12 mounted in close proximity to each other in this manner. The charge air cooler 7 has a plurality of parallel pipelines 14 intended to guide the compressed air. A cooling flange 15 is disposed in the gap between the pipelines 14. Air at ambient temperature is adapted to circulate through the gap between the pipelines 14 so that the compressed air inside the pipelines 14 is cooled by the ambient air. The pipeline 14 and the cooling flange 15 are integrated to form a substantially platform-like cooler portion of the charge air cooler 7. The pipeline 14 has an outlet aperture 14a which is connected at various heights to a tank 17 of the charge air cooler fixed at the end of the platform-like cooler part. The function of the tank 17 is to receive cooled compressed air from the pipeline 14. The tank 17 has a base portion 17a for receiving compressed air from the pipeline outlet aperture 14a. The tank 17 has a first curved portion 17b at the upper end of the base portion 17a. Following the first curved portion 17b is a relatively short substantially horizontal portion 17c and a second curved portion 17d. The tank 17 of the charge air cooler terminates at a connecting portion 17 e for connecting the inlet line 6 to the tank 17. The pipeline 14, the cooling flange 15 and the tank 17 of the charge air cooler 7 are advantageously formed from a material having very good heat transfer properties, for example aluminum.

  The second EGR cooler 12 is mounted substantially vertically below the charge air cooler 7. The second EGR cooler 12 has a plurality of parallel pipelines 18 that are intended to guide the exhaust gas that is returned. A cooling flange 19 is configured in the space between the pipelines 18. Air at ambient temperature is adapted to circulate in the gap between the pipelines 18, thereby cooling the exhaust gas in the pipelines 18. The pipeline 18 and the cooling flange 19 together form a substantially platform-like cooler portion of the second EGR cooler 12. The pipeline 18 has an outlet aperture 18a that connects at various heights into the tank 20 of the second EGR cooler 12 adapted to receive the cooled exhaust gas. The pipeline 18 and the tank 20 are advantageously formed from a highly corrosion resistant material, such as stainless steel. The material should also have relatively good heat transfer properties. However, the cooling flange 19 is not in direct contact with the corrosive exhaust gas and can be formed from a variety of materials.

  In the attached state, the tank 17 of the charge air cooler and the tank 20 of the second EGR cooler are connected to each other. The tank 20 of the second EGR cooler has a tubular element 21 at the top, which extends substantially vertically into the tank 17 of the charge air cooler. The function of the tubular element 21 is to direct the exhaust gas from the second tank 20 to the appropriate position in the first tank 17. The tubular element 21 extends in a straight line upward at a substantially central position inside the first tank 17. The tubular element 21 has an outlet aperture 21a located proximate to the first curved portion 17b of the first tank. The outlet aperture 21a is positioned higher than the outlet aperture 14a of the pipeline. Air exiting the outlet aperture 14a flows upward in the tank base portion 17a toward the first curved portion 17b of the tank. Therefore, the outlet aperture 21a of the tubular element is located at a position downstream of the outlet aperture 14a of the pipeline with respect to the main direction of air flow. Tubular element 21 has an upper edge surface 21b that defines an exit aperture 21a. The upper edge surface 21b is positioned in a plane 22 inclined toward the horizontal portion 17c of the tank. Therefore, the edge portion 21b ′ located at the radially outer position in the curved portion 17b is positioned higher than the edge portion 21b ″ located at the radially inner position in the curved portion 17b. Yes. Such a direction of the outlet aperture 21a facilitates exhaust gas flow through the first curved portion 17b and facilitates mixing of the exhaust gas with compressed air within the horizontal portion 17c of the tank.

  The purpose of the tubular element 21 is to prevent the corrosive substances from the exhaust gas from accumulating in the charge air cooler 7. This is because the components of the charge air cooler 7 are usually formed from a material that does not have sufficient resistance to corrosive substances. The outlet aperture 21a of the tubular element thus flows out at a position that is reliably higher than the outlet aperture 14a in the tank 17. Therefore, the exhaust gas exiting from the tubular element outlet aperture 21a is entrained in the direction of ambient air flow by the ambient air flow. Therefore, there is no risk of exhaust gas accumulation in the tubular element 14 and tank 17 of the charge air cooler. For example, when the load on the combustion engine is low and at the same time there is a low ambient temperature, the exhaust gas may be cooled to such a low temperature that corrosive substances in the exhaust gas may condense. When the exhaust gas is cooled to a temperature at which condensate occurs, condensate typically occurs in the tubular element 18 of the second EGR cooler or in the tank 20. If condensate occurs within the vertical tubular element 21, the condensate travels downward and accumulates at the bottom of the tank 20. Since the tank 20 and the tubular element 21 of the second EGR cooler are formed from a material having a very high corrosion resistance such as stainless steel, at least for a short period, from the viewpoint of corrosion that corrosive substances accumulate in the tank 20. There is almost no fear.

  The invention is in no way limited to the embodiments described, but can be varied freely within the scope of the appended claims.

1 schematically shows a system for recirculation of exhaust gas of a supercharged combustion engine. FIG. FIG. 2 shows a cooler device according to the invention.

Claims (10)

At least one pipeline (14) for guiding compressed air during cooling, and a tank adapted to receive the cooled compressed air from the first pipeline (14) through an outlet aperture (14a) ( A charge air cooler (7) itself having 17);
At least one second pipeline (18) for guiding the exhaust gas during cooling, and a tank adapted to receive the cooled exhaust gas from an outlet aperture (18a) of the second pipeline (18) A cooler device having an EGR cooler (12) having (20),
The cooler device has a tubular element (21) extending from the tank (20) of the EGR cooler to the tank (17) of the charge air cooler, and the tubular element (21) is for the exhaust gas Outlet aperture (21a), the outlet aperture (21a) being the most downstream outlet aperture in the tank (17) of the charge air cooler with respect to the main direction of air flow in the tank (17) (14a) A cooler device, which is located downstream of the cooler device.   The cooler device according to claim 1, characterized in that the tubular element (21) has a portion extending into the tank (17) of the charge air cooler.   The cooler device according to claim 1, characterized in that the tubular element (21) has a substantially linearly extending part inside the tank (17) of the charge air cooler.   4. Cooler according to claim 2 or 3, characterized in that the tubular element (21) has a substantially centrally extending part inside the tank (17) of the charge air cooler. apparatus.   The tank (17) of the charge air cooler has a curved portion (17b) and the outlet aperture (21a) of the tubular element is arranged in the curved portion (17b). The cooler device according to any one of claims 1 to 4.   An outlet aperture (21a) of the tubular element is defined by an end face (21b), the end (21b) being the radially outermost part (21b ′) of the end face within the curved portion (17b). 5. The cooler device according to claim 4, wherein the end face is inclined so as to be located downstream with respect to the radially innermost part (21 b ″) of the end face.   The cooler device according to any one of claims 1 to 6, characterized in that the tank (17) of the charge air cooler is mounted on the tank (20) of the EGR cooler. .   8. The cooler device according to any one of claims 1 to 7, characterized in that the tubular element (21) is made of stainless steel.   9. The cooler device according to claim 1, wherein the EGR cooler (12) is mainly made of stainless steel.   The cooler device according to any one of claims 1 to 9, characterized in that the charge air cooler (7) is mainly made of aluminum.

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